Welcome from Oceanside!
I'll echo what others have said above, and simply state the "more with less" route until you figure out what trails you really enjoy.
As Toro stated above, a few of us started on the "rock crawler Xterra" route and then detoured back to "overlanding/expedition Xterras".
Armoring up for off roading is good advice, because a $200 gas tank skid can save you from a $1,200 tank remove & replacement.
Speaking personally, I wanted to run Moab...bad...back in 2009 when I bought my Xterra.
So I equipped it with a 2" PRG PML (spacers and shackles), bolted on a set of sliders, mounted up some BFG A/T KO's in the 285/75/65 variety, and headed east...several times.
New owner of blue 2012 4X4!
Proper spotting and picking the correct trails saved me from any serious undercarriage damage, but it did render the Ghost as unsellable with the "never off road" line in the Craigslist ad.
New owner of blue 2012 4X4!
The Ghost...Titan swapped and its final outing to Moab in 2013...
New owner of blue 2012 4X4!
My point with all of this long winded QWERTY wording is...figure out the trails/fire roads/interstate highway destinations you want to travel to, and equip your vehicle appropriately. Take your time...and most importantly...
have fun!!!Just be aware that the more serious your mods become in equipping your rig for off road travel, the more it will compromise the on road manners in the opposite direction...as in decreased mileage, acceleration, and day to day reliability.
Hope to see you on the trail soon....John/the infamous GeoYota